The effective and reliable performance of any pump can be significantly impacted by the piping system design. One of the essential points is the pump suction pipe. Poor design and dimension of the suction piping can lead to cavitation in the pump which affects its head and efficiency. The primary objective is to reduce the hydraulic losses of the suction piping in order to maintain a Net Positive Suction Head required by the pump. Suction piping is recommended to be short and straight, and branch connections, valves and elbows should be avoided, which is not always possible. In addition, cavitation can occur in the actual hydraulic elements installed on the pump suction. This work is focused on the investigation of cavitating hydraulic element in the suction pipe on the pump performance. A converging-diverging nozzle with a circular cross-section was used for this purpose. A straight pipe segment of constant diameter and the same length was used for comparison. Both elements were characterized by the loss coefficient and the cavitation number. Their influence on the pump head and the Net Positive Suction Head Available (NPSHA) was investigated.

The paper deals with the application of different types of pumps in emergency pumping system. Two booster pumps increase the pressure of pumped water to achieve the suction pressure required by the main diesel pump. Design of pumping circuit with application of different types of booster pumps drives is presented (hydraulic, hydrodynamic, electrical drive). The pump curves obtained by numerical modelling are used as the input data for further analysis. The mutual interaction of all pumps is investigated to ensure the effectively operating pumping system.

Twin-screw pumps employ clearances between both screws and screw rotors and housing, which cause backflow as function of pressure differential. Reduction of this flow can be reached by proper geometry design. For the experimental investigation, the scaled model 1:2 of the screws section was produced with trapezoidal tooth profile in two modifications differing in tooth width and pitch. Measurement of flow characteristics of non-rotating twin-screw model was carried out for validation and possible corrections of the 3D CFD model. The testing was done with non-Newtonian liquid met in the food industry and additionally also with water. Experimental data were partly compared with results obtained from numerical simulations.